1. Field of the Invention
Aspects of the present invention relate generally to wireless communication systems, and more particularly, to methods and communications apparatuses for enhancing positioning measurements.
2. Description of the Related Art
As wireless devices, such as a wireless user equipment (UE), become indispensable, more wireless phone providers are increasing the accuracy in locating a UE. For example, the US Federal Communication Commission (FCC) requires that a wireless phone provider be able, within a 50 meter radius, to locate 67% of wireless emergency calls from a UE, and within a 150 meter radius, locate 95% of wireless emergency calls from a UE. One approach to achieving desired positioning accuracy is to use network assisted observed time difference of arrival (OTDOA) for positioning 3rd Generation Partnership Project (3GPP) long-term evolution (LTE) compliant wireless devices. Based on this approach, the differences in the time of arrival of known signals sent from nearby cells are measured at the UE and the position of the UE is calculated based on the differences of the arrival times. The UEs are usually required to measure the arrival time differences and report them to the networks.
Because the UE is typically a mobile device, the UE is typically mobile. The networks may only know which cell the UE is “camped” on, and thus, can only assume that the UE is somewhere within the coverage of the cell area. However, the area may be quite large. To locate the UE, the networks need OTDOA from a number of cells. In current systems, the UE is provided a search list of 24 or more cells to make OTDOA observations for.
However, the OTDOA neighbor cell list size currently consists of at most 72 cells. The UE needs to blindly search the cells following the order of the search list. This wastes time and power, and significantly increases computations and process load.
Therefore, wireless communications apparatuses and methods for reducing power consumption and process load are required.